The present application relates to compositions and a method for coloring hair.
Consumers use hair color products for a variety of purposes, usually focused on enhancing their appearance. A new hair color may be desired for an evening (for example, a holiday or party) or for a longer period of time (for example, until the hair grows out). To meet these needs, three categories of hair colors have been developed: temporary, semi-permanent, and permanent. This application relates to all classifications of hair colors.
Temporary hair color products can be removed by shampooing, which offers appeal to consumers wanting the option to change hair color often. To achieve this effect a mild hair color treatment can be used, which causes minimal damage to the hair. However, temporary colors can stains and leach due to rain, high humidity, or perspiration.
Unlike their temporary counterpart, semi-permanent hair colors are removed from the hair gradually with repeated washing, and typically last for about 4 to 6 shampoos. Semi-permanent hair color products may be provided in the form of a rinse, and they cause minimal damage to the hair.
Permanent hair colors, also known as oxidative hair color, utilize a different chemical delivery system than the other two methods. Typically, these products are sold in the form of a kit that has at least two parts. The first part is a color base, or a dye base, and usually is packed in a container having an aqueous alkaline composition in the liquid, gel, or crème form that contains oxidative dyes, an alkalizing agent which is most often ammonium hydroxide, and optionally one or more fatty acids. The other part is the developer, which contains an oxidizing agent, usually hydrogen peroxide. The parts of the permanent hair color kit are mixed immediately prior to use to create the color mix, which is then applied to hair. Directions for the most popular permanent hair colors suggest the color mix be left on hair for about 20 to 60 minutes, and then rinsed off with water. Consumers expect permanent hair colors to last longer than temporary and semi-permanent hair colors, and may in fact last for six weeks or more.
Permanent hair color kits offered for sale often contain more than two components. For example, additional parts may be included to help nuance the final hair color, impart conditioning, and/or shine. Like two-part hair colors, these additional components are blended with the color base and developer before applying to hair. In some hair color products a post-treatment conditioner also is provided, which is worked into hair after coloring and then removed by rinsing in the shower.
Consumers also expect many performance attributes from hair color products. The desired color mix should be easy to prepare from the various components, not drip or run (for example, onto the face or into the eyes), have a pleasing texture, be easy to spread/distribute through the hair, and rinse out easily. To achieve these qualities, the manufacturers of hair colors require hair color ingredients that are non-toxic, broadly compatible, and extend formulation flexibility. However, hair color, especially the color mix, are difficult to thicken, and the available methods can restrict formulation flexibility.
The present inventors have observed that because the viscosity of hair color products can change (for example, on storage), it may be difficult to obtain a homogeneous mixture when these compositions are mixed. In addition, their inconsistency may make them difficult to use.
For example, a review of popular hair color products shows the most common thickeners are: (a) fatty alcohols, amides, and acids that precipitate at the alkaline pH of the color mix, (b) polymers that are alkali swellable, like crosslinked poly(acrylic acid), and (c) polymer/surfactant combinations that interact to create associative complexes.
Thickeners in the prior art and used in other personal care arts may not perform in hair colors. One deficiency is formulation instability due to the change in pH once the color base and developer are mixed. Thickeners may exhibit stringiness or incompletely dissolve and form “fish eyes.” Other thickeners may not make it possible to obtain intense and chromatic shades of low selectivity and good fastness and to offer a good cosmetic condition to the treated hair. Moreover, it has been observed that most of the ready-to-use dyeing compositions of the prior art comprising at least one oxidation dye, and a thickening system may not allow a sufficiently precise application without running or drops in viscosity over time. Hence, needed is an improved thickening system that promotes an appropriate viscosity to avoid dripping and running of the color mix product, is stable, and does not interfere with color shade, coverage, or uniformity.
As it will be explained, the present application is related to lightly- to moderately-crosslinked poly(N-vinyl-2-pyrrolidone) (PVP). This polymer was first introduced in U.S. Pat. No. 5,073,614. In that patent it is taught to be the precipitation polymerization product of N-vinyl-2-pyrrolidone monomer in an organic solvent, such as an aliphatic hydrocarbon solvent (preferably cyclohexane or heptane) or an aromatic hydrocarbon (such as toluene) in the presence of about 0.2% to 1% by weight of a crosslinking agent. The fine, white powders thus produced have an aqueous gel volume of about 15 mL to 150 mL of polymer, and a Brookfield viscosity in 5% aqueous solution of at least about 10,000 cP.
Lightly- to moderately-crosslinked PVP also was the subject of U.S. Pat. No. 5,139,770. Examples are provided in this patent for a cream rise (pH of 4), a hair conditioner (pH of 4), and a blow dry styling lotion (pH of 6), which have been pH-adjusted by the addition of citric acid or phosphoric acid.
U.S. Pat. No. 5,716,634 teaches a lightly-crosslinked N-vinyl lactam polymer in form of stable, clear, flowable, homogenized hydrogel, may be used as a carrier for cosmetic/pharma active for hair or skin use. Also, the production of lightly- to moderately-crosslinked PVP in an oil-in-water or water-in-oil emulsion is taught in U.S. Pat. No. 6,177,068.
Three pending PCT applications also disclose lightly- to moderately-crosslinked PVP in the personal care arts. WO 2010/105050 teaches substantially anhydrous, substantially non-alcoholic personal care compositions having the above-named polymer. WO 2010/105052 provides for compositions having at least: (a) one personal care acid at 0.5% addition level or more, or one pharmaceutical acid at 0.5% addition level or more, and (b) lightly- to moderately-crosslinked PVP. The third application, WO 2010/105030 claims composition comprising: (a) at least one active ingredient selected from the group consisting of an antiperspirant active and a deodorant active; and (b) a thickening agent, wherein the thickening agent comprises a strongly swellable, lightly to moderately crosslinked polyvinyl pyrrolidone.
A summary of some properties of light- to moderately-crosslinked poly(N-vinyl-2-pyrrolidone) is given in Shih, J. S., “Characteristics of lightly crosslinked poly(N-vinylpyrrolidone),” Polymer Materials: Science & Engineering Preprint, 72, 374, 1995.
Still more information on this lightly crosslinked poly(N-vinyl-2-pyrrolidone) polymer is given in the following U.S. Pat. Nos. 5,162,417; 5,312,619; 5,622,168; 5,564,385; and 6,582,711.
The three U.S. Pat. Nos. ('614, '770, '634), the three published PCT patent applications ('050, '052, '030), and the Shih article mentioned in the above paragraphs are hereby incorporated in their entirety by reference.